Characterization of Fiber Bragg Grating Based, Geometry-dependent, Magnetostrictive Composite Sensors

Abstract

Optical sensors based on geometry dependent magnetostrictive composite, having potential applications in current sensing and magnetic field sensing are modeled and evaluated experimentally with an emphasis on their thermal immunity from thermal disturbances. Two sensor geometries composed of a fiber Bragg grating (FBG) embedded in a shaped Terfenol-D/epoxy composite material, which were previously prototyped and tested for magnetic field response, were investigated. When sensing magnetic fields or currents, the primary function of the magnetostrictive composite geometry is to modulate the magnetic flux such that a magnetostrictive strain gradient is induced on the embedded FBG. Simulations and thermal experiments reveal the thermal limitations and geometry dependence of the sensors. Also, during the course of this study, new insights into the effects of environmental factors and sensor manufacturing techniques where uncovered which warrant further investigation.